Why do i need two?

i'm applying for a position at a hospital and the papers say i need two tb skin tests? y? i asked an employee and he said that they only need to get one a year

I have the correct answer for this one - you are given two TB tests because of the "boosting" effect. Occasionally, as a health care employee, if you have been exposed to TB in the past you may not react to the first test. After you are given the first PPD blister under your skin it may reactivate or "wake up" your immune response. The second test, therefore would be positive. It is very common to give two TB tests to health care workers.

Working for an ambulance company, we need two per year as well. Not sure why, that's just the rules :o)

I think every Medical job makes you do two?